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I have discovered two images (see below) and I do not find an explanation for the different color of the sky as seen from below the parachute just starting to deploy. The video with the test performed on Earth says that the altitude was chosen in such a way as to simulate the conditions on Mars.

enter image description here

See: Testing a Parachute for Mars

enter image description here

See: Real Footage of The Perseverance Rover Landing on Mars

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    $\begingroup$ In both videos the color and brightness of the sky varies rapidly, depending on both altitude, instantaneous camera angle with respect to the Sun, and affected by probably exposure setting and color balance. It does not make sense to compare one screen shot to another screen shot. There are many questions and answers about sky brightness and color here in Space SE, in Astronomy SE, Physics SE and Earth Science SE and several Wikipedia articles. $\endgroup$ – uhoh Feb 24 at 7:41
  • $\begingroup$ No, the color of the sky does not change as long as the parachute does not cover the view of the camera. This is the reason I posted two pictures (on Earth and Mars) just before the moment the parachute opened. $\endgroup$ – azot Feb 24 at 8:03
  • $\begingroup$ @azot No. uhoh is correct. The sky colours do change. For example. At 2 sec in the Perseverance Footage, the sky has a tint of blue. But at 11 sec into the footage, the sky is now much darker. $\endgroup$ – Star Man Feb 25 at 4:54
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    $\begingroup$ @azot: the apparent colour of the sky changes dramatically as the parachute opens because the camera is adjusting its exposure as now there is an enormous bright thing (the parachute) in its field of view, and its metering therefore compensates as it doesn't want to have most of that bright thing appear as blown out whites. See Schwem's answer which talks about this. $\endgroup$ – user21103 Feb 25 at 10:13
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    $\begingroup$ I’m voting to close this question because the OP is pushing a theory that the Mars landing is fake. $\endgroup$ – Organic Marble Feb 27 at 3:41
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Hard to say, there's a lot of factors at play. Different angle relative to the Sun. Different solar intensity. Different atmosphere. Different cameras. Different exposures. The only thing that's the same is the air density and parachute. You're going to get different pictures.


That video is from the third JPL ASPIRE (Advanced Supersonic Parachute Inflation Research Experiment) test. It's at 38km to simulate 10 km above Mars.

When onboard sensors determined the payload had reached the appropriate height and Mach number (38 kilometers altitude, Mach 1.8), the payload deployed a parachute...

"Earth's atmosphere near the surface is much denser than that near the Martian surface, by about 100 times," said Ian Clark, the test's technical lead from JPL. "But high up – around 23 miles (37 kilometers) – the atmospheric density on Earth is very similar to 6 miles (10 kilometers) above Mars, which happens to be the altitude that Mars 2020 will deploy its parachute."

38 km is well above where airliners fly, high in the stratosphere. Mars does not have a permanent stratosphere, 10 km is within Mars's troposphere.

The test launch happened Sept 7th at 13:30 UTC which is 09:30 at the Virginia launch site, early in the day which will make the sky darker. I don't know the time of day on Mars when Perseverance landed, but the Sun appeared much higher in the sky.


A lot of things can effect the color of the sky. Altitude, air density, chemical makeup, particulate matter, angle of the Sun (ie. time of day), distance to the Sun, and angle of view relative to the horizon. Mars's atmosphere is very different than the Earth's, the only attribute which is the same between those two videos is the density. Mars's atmosphere and Earth's atmosphere are very different and will reflect light differently.

A lot of things can effect the color of a picture of the sky. Pictures and videos are not true representations of what you would see, they are chosen. These videos are to observe the behavior of the parachute and will be calibrated for that, not to get the true color of the sky, and they're using different cameras with different characteristics. Phil Plat discusses calibration problems on Mars.

In this video discussing the parachute opening at 18:35 you can see the sky color dramatically change as the parachute deploys and the camera adjusts its exposure levels.

Mars 2020 just before inflation, over-exposed.

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Mars 2020 just after inflation, under-exposed.

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This is because the first shot is over-exposed making the dark sky look bright, and the light parachute chord and spacecraft are blown out. The second is under-exposed, the sky is dark and the parachute and spacecraft are under-exposed.

This is not because it blocks the Sun, the Sun is off to the left side somewhere and would not affect the exposure levels.

We see the same effect in the test video, though less pronounced.

ASPIRE just before inflation.

enter image description here

ASPIRE just after inflation.

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There's still a difference, but this provides a better apples-to-apples comparison than the images use in your question.

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  • $\begingroup$ I think the things that are the same are the air density and the parachute. Probably this means the pressure is similar of course, but it's the density that matters. (But this is a good answer IMO.) $\endgroup$ – user21103 Feb 25 at 13:21
  • $\begingroup$ @tfb Thanks, I've fixed that. $\endgroup$ – Schwern Feb 26 at 3:09
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To have on Earth same airpressure of Mars at parachute-opening-altitude you must go very high in the sky, as pressure on Mars is 1/100 than Earth. So you must go "almost in space" to test a Mars parachute on Earth (don't know exact altitude) Hence you see black sky.

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  • $\begingroup$ I understand but as long as on Mars the pressure is only 1/100 that on Earth, it is like you are almost in space! $\endgroup$ – azot Feb 24 at 19:38
  • $\begingroup$ Also, assuming they're looing for a particular atmospheric pressure, because Earth's gravity is 2.5x higher, and its atmosphere is generally warmer, you can get the same pressure with less mass of atmosphere above you over Earth, than on the surface of Mars, even neglecting the significantly different gas composition. $\endgroup$ – notovny Feb 24 at 23:13
  • $\begingroup$ Similar conditions does not mean same pressure but same density of the atmosphere, on Earth and Mars. The pressure is not so relevant for a parachute. The Drag is in general independent of pressure. $\endgroup$ – azot Feb 25 at 4:55
  • $\begingroup$ At the same pressure, CO2 is about 53% more dense than earth air, so the difference is noticeable, but within the same order of magnitude. $\endgroup$ – Aaron Feb 26 at 6:04
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It depends a lot on the sun angle, and exposure settings. For example, here's the a screenshot from the Perseverance descent:

enter image description here

It's a dark sky. You can see the Sun on the bottom left corner. So the camera is clearly much closer to pointing to the Sun. It's also important to keep in mind that there is a bit of dust which does scatter a bit of blue light.

Secondly (and most importantly), the camera is slightly overexposed. This is evident when the parachute fully opens, and the camera immediately adjusts its exposure.

So the reason is most definitely lighting, and the fact that the camera was slightly pointed at the sun. I am quite positive that if the Earth test camera was overexposed as the Perseverance camera was initially, you would see a tint of blue colour (perhaps not as much because of the sun angle).

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  • $\begingroup$ This is the third time when I explain that the black sky appears on Mars at the very moment the parachute opens. The effect is evidently due to the parachute blocking the view of the camera. $\endgroup$ – azot Feb 25 at 6:10
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    $\begingroup$ The effect is evidently due to the parachute blocking the view of the camera. No. That's not the direct reason the sky got darker. The camera automatically adjusted its exposure (as I stated in my answer). That's what caused the sky to get darker. You could think of it similar to something like auto-focus. $\endgroup$ – Star Man Feb 25 at 16:36
  • $\begingroup$ Do you imply that there is no connection between the opening of the parachute and the color of the sky getting considerably darker exactly the same moment? $\endgroup$ – azot Feb 25 at 17:38
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    $\begingroup$ @azot There is a connection. But saying "the sky went dark because of the parachute opening" is not wrong per se, but misleading. The most accurate way is saying "the sky went dark because the camera adjusted its exposure". See Schwern's answer The camera automatically adjusted its exposure when it saw the gigantic parachute in it's FOV. So there is a connection. But that's not the direct reason the sky went dark. $\endgroup$ – Star Man Feb 25 at 18:03
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Not that I disagree with any of the other answers that it's largely impossible to judge the camera exposure, but one thing not yet discussed is that the phenomenon that makes the sky bluish is different between mars and earth. On earth the sky looks colored/bright due to Rayleigh scattering of light off nitrogen and oxygen, but on mars it's dominated by Mie scattering of light off of dust particles. If there was no dust in the atmosphere on mars, it would look similarly black. On earth, there's very little dust in the atmosphere at such a high altitude where the pressure is similar to mars. There have been no geologic processes active on mars for a long time which would strongly condense dust back into solid rock, so it's just a lot dustier than earth.

EDIT: This page has some good explanations and diagrams on the difference between different types of scattering.

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  • $\begingroup$ On Earth the atmosphere looks blue no matter what direction (up or down) you look through it, assuming there is enough gas above or below you (when you are in a plane for instance). The question is: Why is the sky of Mars bluish as seen from a certain altitude and at the same time, why is Mars reddish while viewed from orbit. That Mie scattering should make the red planet look bluish. $\endgroup$ – azot Feb 26 at 7:17
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    $\begingroup$ @azot: why is the moon white when you look at it in the daytime sky? Why is he Sahara brown when seen from space? Because, under a clear sky, about 5 times as much light reaches the surface directly from the Sun as does from the diffuse sky radiation. $\endgroup$ – user21103 Feb 26 at 11:09
  • $\begingroup$ "about 5 times as much light reaches the surface directly from the Sun as does from the diffuse sky radiation"?!! For our case, it is important what reaches the objective of the camera not the surface (of the planet). $\endgroup$ – azot Feb 27 at 0:24
  • $\begingroup$ The moon is bluish if it is visible in the daytime (see: beyultreks.com/?attachment_id=2698). It is not white. $\endgroup$ – azot Feb 27 at 0:31
  • $\begingroup$ @azot: Yes, and every bit of light which reaches the lens of the camera from the surface to make an image of the surface has ... previously reached the surface from somewhere. But I give up: nothing I can say will persuade you of anything, I'm sure. $\endgroup$ – user21103 Feb 27 at 14:51

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